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ZnO rod decorated with Ag nanoparticles for enhanced photocatalytic degradation of methylene blue
摘要： Silver-zinc oxide nanocomposite (Ag-ZnO nanocomposite) were synthesised with different concentrations of Ag doped to the ZnO for enhance photocatalytic degradation of methylene blue. The structures, morphologies, and optical properties of synthesised nanocomposites were characterized by UV-Visible spectroscopy (UV-vis) scanning electron microscopy (SEM), X-ray diffraction (XRD), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FRIR), and photoluminescence spectroscopy (PL). The average size of the synthesized Ag nanoparticles was around 40 nm and ZnO nanorod were 2 μm in length and 200 nm in width. The morphological characterization revealed that Ag nanoparticles were well doped with the ZnO rod surface. The performance and stability of the nanocomposites for the photocatalytic degradation of methylene blue under ultraviolet (UV) light irradiation were evaluated. The overall results suggested that, 6% of Ag nanoparticles achieved better degradation than compare to the other concentrations and bare ZnO. This work provides a simple and effective route to prepare Ag-ZnO nanocomposite for effective degradation of methylene blue. Therefore, Ag-ZnO nanocomposite can be regarded as a potential candidate for application in the treatment of waste water.
关键词： Methylene blue,Ag-ZnO nanocomposites,Mechanism,Photocatalysis
更新于2025-09-23 15:23:52
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Facile synthesis of thin black TiO2 ? x nanosheets with enhanced lithium-storage capacity and visible light photocatalytic hydrogen production
摘要： In combination of a facile and scalable solvothermal method and solid-phase reduction reactions, a novel two-dimensional black TiO2 ? x nanosheet (TiO2 ? x NS) with high specific surface area of 108 m2 g?1 and nearly total solar spectral absorption capability have been successfully prepared. With careful characterizations, the novel TiO2 ? x NS showed enhanced electrochemical performance and visible-light photocatalytic activity than those of their white TiO2 nanosheet (TiO2 NS) precursors. The black TiO2 ? x NS electrode delivered a reversible specific capacity of 160 mA h g?1 even after cycling at 0.5 C (1 C = 190 mA h g?1) for 300 times, which was significantly higher than the corresponding white TiO2 NS electrode (104 mA h g?1). Meanwhile, the TiO2 ? x NS also exhibited enhanced ability of visible-light photocatalytic hydrogen production than that of the white TiO2 NS. It is expected that making white TiO2 NS into black ones is an effective way to design the photocatalysts with visible light response and the anodes with long lifetime and high rate performance in lithium ion batteries. The novel black TiO2 ? x NS could find potential applications in the field of environmental management and energy storage and conversion.
关键词： Solvothermal method,Photocatalysis,Black TiO2 ? x nanosheets,Anodes
更新于2025-09-23 15:23:52
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UV and visible-light driven photocatalytic removal of caffeine using ZnO modified with different noble metals (Pt, Ag and Au)
摘要： In this work, ZnO photocatalyst was modified with different noble metals (Pt, Ag and Au) through photo-deposition method and then characterized by different techniques (XRD, XRF, BET, UV–vis DRS, FESEM, and XPS). The addition of noble metals produces important changes in the light absorption properties with a significant absorbance in the visible region due to the existence of surface plasmon resonance (SPR) observed at about 450 nm and 550 nm for ZnO modified with Ag and Au, respectively. The morphology of the samples was studied by TEM and the size ranges of the different metals were estimated. Noble metal nanoparticles were in every case heterogeneously deposited on the larger ZnO particles. All the prepared photocatalysts were tested in the photocatalytic removal of caffeine (toxic and persistent emerging compound) under UV and visible light irradiation. It was observed an enhancement of photocatalytic caffeine removal from aqueous solutions under UV light irradiation with the increase of metal content (from 0.5 to 1 wt %) for ZnO modified with Ag and Au (Ag/ZnO and Au/ZnO). In particular, Ag/ZnO and Au/ZnO with higher Ag and Au content (1 wt %) allowed to achieve the almost complete caffeine degradation after only 30 min and a TOC removal higher than 90% after 4 h of UV light irradiation. These two photocatalysts were investigated also under visible light irradiation and it was found that their photocatalytic performances were strongly enhanced in presence of visible light compared to unmodified ZnO. In particular, Ag/ZnO photocatalyst was able to reach the complete caffeine degradation and a TOC removal of about 70% after 4 h of visible light irradiation.
关键词： Caffeine removal,Photocatalysis,ZnO,UV and visible light,Noble metals
更新于2025-09-23 15:23:52
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Thermal evolution of morphological, structural, optical and photocatalytic properties of CuO thin films
摘要： Nanostructured CuO thin films were synthesized by thermal evaporation and annealing. Structural, optical and morphological changes in the CuO film upon annealing and their overall impact on its photocatalytic activity were investigated employing X-ray diffraction, UV–Vis absorption spectroscopy, atomic force microscopy and field emission scanning electron microscopy. Significant modifications in the morphological, optical, structural and photocatalytic behavior of nanostructured CuO thin film were observed upon thermal annealing. Thermal annealing led to the growth of CuO nanoparticles and the average size of CuO nanoparticles increased from 23 nm to 293 nm as the annealing temperature was increased to 600oC. CuO thin film sample annealed at 400 ? C exhibited superior photocatalytic activities over other samples for the degradation of malachite green and methylene blue dyes in 120 and 160 min, respectively. The improved photocatalytic behavior of CuO thin film annealed at 400 ? C is attributed to its narrower band gap, improved utilization of sunlight and enhanced adsorption of dye due to increased surface area arising from formation of CuO nanoparticles and their aggregates at the surface.
关键词： Methylene blue,CuO,Thin film,Photocatalysis,Malachite green
更新于2025-09-23 15:23:52
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Construction of Self-Healing Internal Electric Field for Sustainably Enhanced Photocatalysis
摘要： The construction of internal electric field is generally considered an effective strategy to enhance photocatalytic performance due to its significant role in charge separation. However, static internal electric field is prone to be saturated either by inner or outer shield effect, and thus its effect on the improvement of photocatalysis can easily vanish. Here, the self-healing internal electric field is proposed and successfully endowed to a designed helical structural composite microfiber polyvinylidene fluoride/g-C3N4 (PVDF/g-C3N4) based on the bioinspired simple harmonic vibration. Importantly, the saturation and recovery of internal electric field are characterized by transient photovoltage and photoluminescence. The results indicate that the internal electric field could be saturated within about 10 min and refreshed with the assistance of rebuilt piezoelectric potential. The lifetime of photogenerated carriers is about 10?4 s and the number of effective carriers is greatly increased in the presence of self-healing internal electric field. The results provide direct experimental evidence on the role of self-healing internal electric field in charge transfer behavior. This work represents a new design strategy of photocatalysts, and it may open up new horizons for solving energy shortage and environmental issues.
关键词： charge separation,photocatalysis,microfluidics,bioinspired,self-healing
更新于2025-09-23 15:23:52
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Efficient Conversion of CO <sub/>2</sub> to Methane Photocatalyzed by Conductive Black Titania
摘要： One of the major challenges encountered in CO2 utilization is the development of available and cost-efficient catalysts with sufficient activity, selectivity, and stability for the generation of useful methane. Here, conductive black titania, TiO2@x, is found to be efficient in photocatalyzing the reduction of CO2 to CH4. This unique material comprises a crystalline core–amorphous shell structure (TiO2@TiO2@x) with numerous surface oxygen vacancies, which facilitates the adsorption and chemical activation of CO2 molecules. Under full solar irradiation, the optimized 500-TiO2@x material with narrowed band gap and intermediate states below the conduction band tail exhibits a high space-time yield of CH4 of 14.3 mmol g@1 h@1, with 74 % selectivity and excellent photostability. The present findings can make a significant contribution, not only to develop the surface electron-modified black TiO2 catalyst to boost photocatalytic efficiency, but also to establish a really viable and convenient CH4 production process for CO2 conversion and renewable solar energy storage.
关键词： oxygen vacancies,photocatalysis,carbon dioxide chemistry,conductive black titania,methane generation
更新于2025-09-23 15:23:52
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Facile preparation of KBiO <sub/>3</sub> /g-C <sub/>3</sub> N <sub/>4</sub> composites with microwave irradiation for photocatalytic hydrogen production
摘要： BACKGROUND: KBiO3/g-C3N4 composites were prepared under microwave irradiation to different weight ratio of KBiO3 (5, 10, 20, 30, 40, 50, 60, 70 80, 90 %wt) using a Mars-6 for 30 min at 100 W. The samples were characterization by XRD, FT-IR, SEM, EDS-Mapping, N2 physisorption and DRS. The photocatalytic activity of the samples was evaluated in the hydrogen evolution reaction. RESULTS: The composites were confirmed by XRD, where was observed that the samples up to 60% of KBiO3 it is easy to identify the characteristic peak of g-C3N4. Composites show that KBiO3 was homogeneously dispersed on g-C3N4 according to what was observed by EDS-Mapping. In the photocatalytic tests was observed that when the concentration of g-C3N4 is greater than KBiO3 but up to a certain limit, there is a higher production of hydrogen. CONCLUSIONS: KBiO3/g-C3N4 composites were prepared successfully with microwave irradiation reaching a good synergy between both materials for hydrogen production reaction. This synergy was improved to the use of microwave that facilitates the dispersion and binding of both materials. The sample with best hydrogen production was 40%KBiO3/60%C3N4 with 698 μmol H2/g, which is about 3 times higher than g-C3N4 and 7 times higher than KBiO3.
关键词： KBiO3/g-C3N4,photocatalysis,hydrogen production,microwave method
更新于2025-09-23 15:23:52
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Electrostatically Directed Assembly of Nanostructured Composites for Enhanced Photocatalysis
摘要： It is well established that the activity of photocatalysts can be improved by deposition of redox catalysts, which can effectively extract the photogenerated charge carriers, enhance the rate of interfacial reactions, and thus suppress undesired recombination processes. For optimum performance, a high degree of control over the loading, size, and surface catalytic properties of redox catalyst particles is desirable. Herein, a novel, highly controllable, and versatile method for preparation of TiO2 catalyst composites is reported. It starts with the generation of “naked” (ligand-free) nanoparticles of CuOx or FeOx by pulsed laser ablation of metal oxide targets in water. In the next step, a nearly quantitative colloidal deposition of CuOx and FeOx nanoparticles onto anatase TiO2 substrate is achieved by adjusting the pH in order to establish electrostatic attraction between the colloids and the substrate. The resulting TiO2–CuOx and TiO2–FeOx assemblies with optimum catalyst amount (≈0.5 wt%) exhibit photocatalytic rates in degradation of 2,4-dichlorophenoxyacetic acid enhanced by a factor of ≈1.5 as compared to pristine TiO2 under simulated solar irradiation. The electrostatically directed assembly of TiO2 with ligand-free catalyst nanoparticles generated by pulsed laser ablation is thus demonstrated as a viable tool for preparation of composites with enhanced photocatalytic performance.
关键词： photocatalysis,titanium dioxide,laser ablation,colloidal deposition,nanoparticles
更新于2025-09-23 15:23:52
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Ag/Ag2O/BiNbO4 structure for simultaneous photocatalytic degradation of mixed cationic and anionic dyes
摘要： In principle, n-type and p-type semiconductors are respectively responsible for photo-catalytic degradation of cationic dyes (e.g., methylene blue) and anionic dyes (e.g., acid red 1), governed by photoelectrons in the former and photo-holes in the later system. Hence, we present a new strategy: design and fabrication of photocatalytic structures to match the redox potentials of mixed basic/acidic dyes as well as the reactive oxygen species (ROS). For the ?rst time Ag/Ag2O/BiNbO4 structure is (1) designed to match the redox potentials of basic/acidic dyes as well as ROS, (2) fabricated using photoreduction to control the Ag/Ag2O/BiNbO4 interfaces, and (3) able to simultaneously degrade 84% methylene blue dye (MB) in 240 min and 88% acid red 1 (AR) in 25 min under LED light irradiation, corresponding to 7 wt% Ag loading. To the best of our knowledge, this is the ?rst photocatalytic degradation study on mixed basic and acidic dyes using a single catalyst. We also tested the new redox potential matching strategy in mixed basic dyes (MB and rhodamine B (RhB)). As expected our experimental results reproduced well our model predictions: in particular, results support our proposed hydroxyl radical (?OH) mechanism, which is initiated by photo-holes. Therefore, this new design strategy, which consists of matching band structures of the photocatalyst with redox potentials of dyes and ROS, has immediate implications to general photocatalytic applications beyond dye degradation and water-splitting.
关键词： Methylene blue,Nanostructures,Rhodamine B,Photocatalysis,Dye degradation,Acid red,Mixed dyes
更新于2025-09-23 15:23:52
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Enhanced solar induced photo-thermal synergistic catalytic CO2 conversion by photothermal material decorated TiO2
摘要： Semiconductor material with narrow bandgap is an ideal photo-thermal conversion material because of its high absorption intensity in infrared region. Here, CuS/TiO2 composites were synthesized based on UV-responsive TiO2 compound with narrow bandgap semiconductor material CuS for CO2 conversion under full-spectrum irradiation. The experimental results showed that 2% CuS/TiO2 exhibited higher photocatalytic CO2 reduction efficiency due to the solar induced photo-thermal synergistic effect. CuS can absorb and convert infrared light into heat energy, which promotes the utilization range of sunlight for CO2 conversion. In-situ Fourier transform infrared spectroscopy (FT–IR) was used to explain the photocatalytic mechanism at the molecular level. This work suggested a feasible way for integrated utilization of solar energy by narrow bandgap semiconductor compounds with TiO2 to convert CO2.
关键词： TiO2,photocatalysis,solar,CuS,CO2 conversion
更新于2025-09-23 15:23:52